Effect of synthesis route on the structural, magnetic and magnetocaloric properties of La0.78Dy0.02Ca0.2MnO3 manganite: A comparison between sol-gel, high-energy ball-milling and solid state process

Abstract

La0.78Dy0.02Ca0.2MnO3 compound has been synthesized using different methods: solid state reaction, sol-gel route and ball-milling process. The Rietveld refinement of X-ray powder diffraction shows that all our samples crystallize in the orthorhombic system with Pnma space group. Morphological properties investigated using Scanning Electron Microscopy (SEM), indicated various microstructure ranging from micrometric grain size (solid-state and sol-gel techniques) to an ultrafine grains one (ball-milling method). Based on Banerjee criterion, Landau theory and universal curve we successfully confirmed that the nature of the magnetic transition changes from first order for the sample elaborated by sol-gel route to second order transition for those synthesized by both solid-state route and ball-milling methods. Therefore, it can be deduced that the process of elaboration presents an intensive impact on the magnetic behavior. The compound elaborated by Ball-milling undergoes the larger magnetocaloric effect (MCE). It exhibits a large relative cooling power (RCP) of 346.70 J/Kg under 5 T. Thus it has the appropriate properties as suitable candidate for magnetic refrigeration application.